[rrd-users] Vedr: rrdtool fetch boundaries

[morten bjoernsvik]

|Fra: Alex van den Bogaerdt <alex at vandenbogaerdt.nl>
|
|> Hi All
|>
|> I'm extracting statistics from lots of rrds using rrdtool fetch, but it
|> seems like
|> fetch is rather fuzzy about the -s and -e settings
|
|A combination of unfortunate accidents with programming off-by-one errors
|and people not understanding the fencepost error
|http://en.wikipedia.org/wiki/Off-by-one_error#Fencepost_error
|
|What usually helps is to ask for {$start_you_want}+{$offset} to
|{$end_you_want}-{$offset} where offset is choosen such a way that it does
|not make another RRA more suitable. Generally speaking "1" is already
|enough.


Thanks Alex


Decreasing the boundaries with a step on each side seem to work ok. for most intervals.

I also use the mean(), median() and standard_deviation() so it does not affect me much.

Thanks for the link to wikipedia article.


--
MortenB